hey wait, you can't bash tuners.... they know best... remember... they are the ones that 'reverse engineered' the software.

here's some interesting info from another thread.

http://forums.corvetteforum.com/show....php?t=1497046

"...One important note--we used the factory GM calibration for this baseline test. Dan points out that that is important because the factory spark tables are based on airflow. As such, the stock computer tends to pull timing (stock GM timing for this engine runs right at 28 to 29 degrees) when it senses an increase in intake air or decreased backpressure with a better exhaust. (This also tells us that bolt-on exhaust and cold-air kits will need a companion tune to maximize horsepower.) Because of this, Dan estimates another 10 to 15 hp could be left on the table with the stock LS2 because there was timing getting pulled during our test runs. ...


...As for the tune, Dan used the stock GM computer (no FAST, Accel, etc.) with proprietary GM software to keep the air/fuel ratio right at 12.5 to 12.7:1. The factory tune in our baseline numbers was 12.5:1, so you can see there isn't any "tuning magic" in the reported number set. However, as we alluded to earlier, Dan did tune the engine to correct for the stock computer pulling timing during the run, which would account for the aforementioned 10 to 15hp difference. ..."

http://www.gmhightechperformance.com...sts/index.html




apparently timing was being pulled on an engine dyno, not the chassis dyno, when using the stock programming.

 

Is there a point to the previous post? If so, I missed it completely.

 

From the reading I have done on TM in general, not just the C6 this is how it is calculated. The torque is sensed by monitoring functions pertaining to the engine and not at the rear wheels.. Makes sense to me, the computer could adjust for it much quicker this way.

 

is it possible the timing being pulled is the TM effect that people are feeling ?

apparently timing was being pulled by the computer when using the stock program. this was on an engine dyno not a chassis dyno.

 

It is only a possibility --- at least per the thread you just cited --- if every person who experienced TM also had a bolt-on exhaust and/or a cold-air kit.

You are comparing apples and avocados. There is no doubt whatsoever that the stock computer adjusts air/fuel and timing in response to a number of parameters. This is not TM.

 

following your logic only folks that have modded with at least a cat-back and or an aftermarket air intake would experience the 'timing retard' as well as everyone that had cat-back/intake would experience it during a run.


"the stock computer tends to pull timing (stock GM timing for this engine runs right at 28 to 29 degrees) when it senses an increase in intake air or decreased backpressure with a better exhaust. (This also tells us that bolt-on exhaust and cold-air kits will need a companion tune to maximize horsepower.)"

this doesn't say that only cold-air kits or cat-back / freer flowing exhaust cause the timing to be pulled, it says the stock computer settings pull timing.

is the increase in flow from sudden and or heavy acceleration sufficient to activate the 'timing retard'.

doesn't the z06 have baffles in the exhaust that cause a freer-flowing exhaust at a specific rpm ? and may thereby activate this 'feature' ?

 

You have a real knack for arguing with yourself. Circular reasoning must be very self-satisfying. Enjoy!

 

Sorry if this has been discussed (I didn't read all 540 prior posts on this thread!), but couldn't the tuner at the least get the engine tuned to run on 93 octane (as opposed to the 91 that the factory sets to)? Also, does anyone know if the 160 degree thermostat does any other bad things to the engine, like causing excess carbon or other buildups?

Thanks.

 

The stock tune will certainly run just fine on 93 octane gas, it just doesn't leverage the higher octane for maximum power. The tuner can easily add a little timing and lean out the A/F mix slightly for a few more ponies.

In my opinion, there are two drawbacks to the lower temp thermo. In very cold weather, the heater may take a little longer to come on, and the engine may produce a bit more emissions at a lower operating temperature. For maximum benefit, the lower temp thermo needs to be coordinated with the fan controls to keep the operating temps consistently within the desired operating range.

I haven't heard of any carbon buildup type issues associated with lowered operating temps, at least with a well conceived setup.

 

Whenever (rarely!) I see a certain pattern in posts that looks roughly like:

"Why did that happen? How do you explain what he said? How come? Where is your proof? Tell me why what I heard is wrong. That's not what some other guy said. Show me... give me... love me..."

and further, the record of posting for that poster is nearly 100% in that vein, with nearly NO fact-based independent contribution, or furthering of the overall body of knowledge by personal observation, experiment, research, expertise, etc...

Well, let's just say my interest in the dialog plummets. I guess the kids would call it a "Buzz Kill".

 

Well stated.

 

this is a direct quote from "Smokey Yunick's Power Secrets" page 121

"Coolant Temp

It is east to see how everheating can be a problem, but I think some racers overlook the fact that it is possible to 'overcool' the engine. Some guys go to great lengths to keep the engine temperature down to 180 degrees. And, though the engine doesn't overheat, they don't realize that they're putting energy (heat) into the cooling system that could be used to produce power at the crankshaft.
Running an engine at 180 degrees will drop the overall horsepower by 2-3%. For max power the coolant temperature should be at least 200 degrees, and you should have at least 25 pounds of pressure in the system. Actually, a racing engine like the small block Chevy will produce more horsepower as the operating temperature is increased, all the way up to a maximum limit of about 220 degrees."

 

i guess you folks have all the answers but don't like to share...

or "alzheimer's". if you've got the answers, provide them.

 

ok, since it appears that, when using the 'stock' programming, timing is pulled at certain thresholds, does anyone know what those threshholds might be ?

 

Yes.

The threshholds are contained in the tuning tables. Go to the HPTuners website, where there are dozens of discussion threads on this topic.

 

who the hell is smokey. that may be true on a road course. but in the 1//4 mile you have to find a medium start low after burn out by the 1/8 you are close by the end you are over

 

here's some info about smokey.

"Aside from racing, Yunick's innovations include variable ratio power steering, the extended tip spark plug, reverse flow cooling systems, a high efficiency vapor carburetor, a high efficiency adiabatic engine, various engine testing devices, and a safety wall for racetracks, made of discarded tires, which France had refused to consider. He was granted twelve patents."

http://en.wikipedia.org/wiki/Smokey_Yunick

"A sly mechanical genius whose reputation as one of the premier mechanics in NASCAR hasn't diminished over the years, Henry Smokey Yunick was the "Best Damn Race Car Mechanic" who worked out of the "Best Damn Garage In Town," in Daytona Beach, Fla."

http://www.motorsportshalloffame.com...unick_main.htm

"The legendaric Smokey Yunick is not just a world champ in fusktrim(?) He is also genious. The best prove so far is called the "Hot Vapor". A new engine which will revolutionize the hole automotive industry. Smokey's self constructed 2 cylinder engine gives the double horsepower as a standard 4 cylinder engine of the same size. Further more is uses much less fuel and exhaust much less polution. Hot Vapor is almost too good to be true. But an enthusiastic Bostic is convinsed. It is true! "

"GM, Ford, Chrysler and many foreign car manufactors comes around in "Best damn garage in town". To stress test Smokeys test cars with the new engine. It is the best engineers from the manufators who show up andd they come several times. Smokey is laughin. They come back because they can not get the engine to spike. Some of them does everything to get the engine spiking. No one has succeseeded. "


http://schou.dk/hvce/


but, this wasn't meant to be a discussion about smokey, but rather some information about running too cool.

 

thanks, any possibility of getting those thresholds posted here instead of going to another site ?

 

Dyno runs would show evidence of torque management, if such a thing existed. I've never seen one that does. I think TM is , outside of traction control--or active suspension if you consider puting on the brakes torque "management." I've never read a word about tm in any car magazine, either. If it existed, they certainly would have had an article about it. Like I said .

 

Sure, be my guest.

Re your other post, about Smokey Yunick, he died in 2001. I remember one of his NASCAR "tricks" was to drill a small hole in the top of his headers. His competitors all thought it was another one of his secret tuning tricks that nobody could quite figure out. Later Smokey revealed that the hole was there so he could see the color of the exhaust gasses, determine the temperature, and then adjust the A/F mix accordingly.

A few comments about his thoughts on operating temps:

1. To my knowledge, he never tuned an LSx aluminum block engine. They do not necessarily have the same thermodynamics as an SBC.
2. Just because an engine has a 160 or 180 degree thermostat in it does not mean that it will operate at that temp. Most of these cars will still operate right around 195-200 degrees, depending on the fan settings, ambient temperature, operating conditions, etc. They just won't heat up as quickly.
3. There are dozens of reputable tuners and suppliers who offer the lower temp thermos, and/or recommend that optimal operating temps for the LSx engine is just under 200 degrees. I don't know of anyone who recommends operating temps above 220 degrees. Hundreds of independent dyno tests confirm this. Smokey MAY be right in theory, but in actual practice a lower operating temp seems to be optimal for LSx engines.